In this study, we investigate the determinants of credit ratings for companies affiliated with the Korean Chaebols. After controlling for endogeneity, we find that the average credit ratings for Chaebol-affiliated firms are significantly higher than those of non-Chaebol-affiliated firms. Next, we estimate the critical control threshold centrality and position established by Almedia et al. (2011) and apply those measures to the credit ratings of affiliated firms. The results show that affiliated firms with lower centrality measures tend to have higher credit ratings and that the relationship is not linear, suggesting that controlling shareholders use central firms to provide firms that have lower centrality with operational and financial support, that is, propping. Firms with lower centrality have higher credit ratings during a group-wide boom. This suggests that propping is more likely to emerge during an economic boom.